1. Technical Field
The invention relates to air springs, and more particularly to the clamping assembly which sealingly affixes a resilient elastomeric sleeve to an end member of the air spring. Even more particularly, the invention relates to a combination swage ring and end member sealing surface in which the swage ring has the more aggressive clamping ribs and grooves than does the end member to reduce the risk of causing leaks on the innerliner of the air spring sleeve.
2. Background Information
Pneumatic springs commonly referred to as air springs, have been used for a variety of uses including motor vehicles for a number of years to provide cushioning between movable parts of the vehicle or other types of equipment, primarily to absorb shock loads impressed on the vehicle axles by the wheels striking an object in the road or falling into a depression. The air spring usually consists of a flexible elastomeric sleeve or bellows containing a supply of compressed fluid and has one or more pistons attached to the flexible sleeve. The piston causes compression and expansion of the fluid within the sleeve as the sleeve compresses and expands as the vehicle experiences the road shock. The spring sleeve is formed of a flexible elastomeric material which permits the piston to move axially with respect to another piston or end member secured within opposite ends of the sleeve.
The ends of the sleeves are sealingly connected to the piston and/or opposite end member and is always one of the important and major aspects in producing an efficient and maintenance free air spring.
Many of these sealing connections are provided by a swage or clamp ring and an end member both of which have a plurality of mating ribs and grooves which provide pinch areas therebetween to securely clamp the elastomeric material and internal reinforcing cord of the sleeve therebetween. Heretofore in these clamping connections, the more aggressive clamping ribs and adjacent grooves engage the innerliner of the air spring sleeve with the less aggressive clamping ribs and grooves engaging the outer cover of the air spring sleeve. Although these types of clamp or swage ring connections have proven satisfactory, problems can occur in that the innerliner of the air spring sleeve can be pinched or cut by the relatively aggressive configuration of the clamping member, whether it be the swage ring and/or end member which can result in loss of air and pressure within the air spring.
The present invention provides an air spring having a flexible sleeve with at least one open end wherein the clamping assembly has the more aggressive clamping projections and grooves which results in the higher stress concentration engaging the outer cover of the air spring sleeve with a less aggressive clamping pattern engaging the innerliner to reduce the risk of damaging the innerliner of the sleeve, which is the main fluid impervious layer which retains the energy absorbing fluid within the air spring.
Another feature of the invention is providing the clamping surface of the swage ring with one or more radially extending ribs which have a greater radial length and tighter radius of curvature than the aligned concave grooves formed on the sealing surface of the air spring end member.
A further feature of the invention is to provide the more aggressive radially extending swage ring ribs with a length approximately twice the depth of the aligned recesses on the end member and providing adjacent grooves in the swage ring with a depth of approximately twice the radial length of the aligned less aggressive ribs formed on the sealing surface of the end member.
Another aspect of the invention is to provide a radially extending shoulder on the end member which limits the axial movement of the swage ring during operation of the air spring.
Another advantage of the invention is to provide both the clamping surface of the swage ring and the clamping surface of the end member with a plurality of projections and adjacent recesses, the number of which can be varied to provide the desired clamping force depending upon the internal pressure contained within the air spring sleeve.